The crosstie memory

The crosstie memory stores information in magnetic domain walls in permalloy films about 350 Å thick. The domain walls are also used as shift register tracks. Serrated edges on narrow thin film permalloy strips are used to center a domain wall in each strip and to provide stable positions for crossties and Bloch lines. A magnetoresistance detector uses the same information bearing permalloy film as the magnetoresistive element. The entire crosstie memory can be fabricated on a silicon wafer or chip using conventional photolithographic procedures as are used in fabricating integrated circuits. Thus, a magnetic memory can be combined with semiconductor drivers, decoders, and sense amplifiers on the same chip. The memory is intended to serve as a block oriented random access memory (BORAM). Important background information such as static and dynamic stability conditions, Bloch line mobility, propagation and observation techniques are reviewed. Also, design goals and the role such device is expected to play in memory technology are presented. Anticipated performance includes a shift rate of 20 × 10⁶bits/sec, a bit density greater than 1.5 × 10⁵bits/cm², an operating temperature range from -50 °C to 100 °C, nonvolatility, low cost, and low power consumption.